Process for obtaining bitumens from underground deposits



H. LANGE Oct., 21, 1969 PROCESS FOR OBTAINING BTUMENS FROM UNDERGROUND DEPOSITS Filed Aug. 4, 1967 To pressure INVENTOR HANS LANGE LUM ATTORNEYS` Unite States Patent O im. ci. nzib 43/24 US. Cl. 16d-261 5 Claims ABSTRACT OF 'II-E DISCLOSURE In a process for the extensive recovery of liquid and solid bitumens from underground deposits comprising:

(a) Locating at least one relatively deep flooding boring, at least one relatively shallow production boring, at least one treatment boring and at least one leading boring, said treatment and leading borings located between said flooding boring and said production boring and spaced a predetermined direction apart from one another in the stratum of an underground deposit of bitumens; and

(b) Introducing into said treatment boring an activated gas of combustion comprising oxygen and hot modified gas of combustion comprising steam and carbon dioxide; the improvement comprising a treatment boring comprising a casing having an upper end, a lower end and a packer intermediate said ends and a preliminary preparation of the treatment boring and initiation of in situ combustion by ignition in the treatment boring, said preparation and initiation comprising:

(c) Filling the space in the treatment boring above the packer which contains traces of oil with water or nitrogen under high pressure;

(d) Providing a gaseous mixture consisting mainly of carbon dioxide and steam;

(e) Heating the gaseous mixture to above 200 C., depending on the pressure and saturation temperature of the steam to form a hot modied gas of combustion;

(f) Introducing the hot modied gas of combustion into the narrowly restricted spaces below the packer of the treatment boring and in its immediate neighborhood thereby displacing any oil that is present;

(g) Increasing the oxygen content in the hot modified gas of combustion from to 21% by volume to form an activated gas of combustion and thereby oxidizing anyl oil that is present below the packer of the treatment boring;

(h) Increasing the temperature of the activated gas of combustion; and

(i) Initiating burning by contacting the activated gas of combustion at the lower end of the treatment boring with combustion catalysts or substances that vigorously react with oxygen.

CROSS-REFERENCES TO RELATED APPLICATIONS Applicant claims priority under 35 U.S.C. 119 for German application Ser. No. D 50,833, led Aug. 12, 1966.

Incorporated by reference herein is the disclosure of applicants copending U.S. patent application, Ser. No. 440,852, tiled Mar. 18, 1965, now U.S. Patent 3,344,856, dated Oct. 3, 1967, which in turn is a continuation-in-part of U.S. patent application Ser. No. 349,589, tiled Mar. 5, 1964, now U.S, Patent 3,360,044, dated Dec. 26, 1967.

The title of the copending application is Process for the Extraction of Liquid and Solid Bitumens From Underground Deposits, and the application relates to a continuous method of extracting liquid and solid bitumens from underground deposits where injection and produc- @Aw Patented Oct. 2l, 1969 rice tion borings are inserted into an underground stratum of the bitumens, combustion gases are fed to the underground deposit and ignited, the bitumens are brought to the surface in liquid and gaseous phases, a portion of the bitumens are recovered, another portion of the bitumens is recirculated into the stratum to be burned by the heat in the reaction zone and a continuous process is provided.

BACKGROUND OF THE INVENTION The field of the invention is processes for supplying input and output to Wells wherein the input includes heating. A particular eld of the invention is processes for heating wells which includes the introduction of heated uid.

The process of U.S. Patent No. 3,344,856, supra, has for an object the production of bitumens from deposits containing liquid bitumens by in situ combustion wherein the in situ combustion is effected in a specially prepared burning zone. According to this invention, incorporated herein by reference, the in situ combustion is effected with a compressed oxygen gaseous mixture containing carbon dioxide and steam. This mixture contains -95% oxygen. When such a gaseous mixture, composed mainly of oxygen, is brought into contact with mineral oil components in the injection or treatment boring, the apparatus elements contained in the borings or the areas in the immediate neighborhood of the borings, a highly explosive mixture is formed. This mixture causes explosions in the neighborhood of the boring or leads to a series of explosive blasts in the deposit. extensive recovery of liquid and solid bitumens from According to this prior disclosure the process for the underground deposits comprises the steps of:

(a) Locating at least one relatively deep flooding boring, at least one relatively shallow production boring, at least one treatment boring and at least one leading boring, said treatment and leading borings located between said flooding boring and said production boring and spaced a predetermined direction apart from one another in the stratum of underground deposit of bitumens;

(b) Introducing into said treatment boring an activated gas combustion comprising oxygen and hot modified gas of combustion comprising steam and carbon dioxide;

(c) Developing a hot reaction zone between at least one of said treatment borings and at least one of said leading borings having a given temperature range by the sensible heat of said gas of combustion and a reaction of a portion of said bitumens and oxygen producing additional modified gases of combustion;

(d) Conducting further into said stratum ahead of said reaction zone said additional modified gases of combustion from (c), where they condense and dissolve to form a liquid phase of the contents of the stratum; and

(e) Advancing said reaction zone and displacing ahead of its the stratum contents with condensed and dissolved gas of combustion in the direction of the production boring by the introduction of Water through said flooding boring, and removing the advanced stratum contents through the production boring.

For initiating the in situ combustion in the burning zone, precautions are necessary in order to permit the introduction and ignition of the gases without danger of explosions.

SUMMARY OF THE INVENTION It is therefor an object of the present invention to avoid explosions associated with the process for obtaining bitumens from underground deposits.

Another object of the present invention is to provide a preliminary preparation of a treatment boring prior to the commencement of an in situ combustion.

Still another object of the present invention is an improved apparatus for insertion in the treatment boring of a process for obtaining bitumens from underground deposits.

Upon further study of the specification, drawings and claims other objects and advantages of the present invention will become apparent.

According to the present invention, the production of bitumens from deposits containing liquid bitumens by the in situ combustion process disclosed in U.S. Patent No. 3,344,856 supra is improved by a process and apparatus for the preliminary preparation of the treatment boring and the commencement of the in situ combustion. The present process and apparatus is characterized in that when the space above the packer located above the injection or treatment borings contains traces of oil, the space is filled with water or gaseous nitrogen under high pressure and through this treatment boring the gaseous mixture consisting mainly of carbon dioxide and steam is injected. The gaseous mixture is heated to above 200 C., depending on the pressure and saturation temperature of the steam. The gaseous mixture is gradually enriched with oxygen from at the beginning to 21% by volume. This gaseous mixture is injected into the restricted space in the boring below the packer and into the immediate neighborhood thereof, to displace and oxidize whatever oil may be present. The temperature of the oxygen containing gaseous mixture is gradually increased and ignition is effected by contacting the gaseous mixture containing oxygen with catalysts or readily oxidizable substances located in the bottom of the treatment boring.

It is important in the present process to provide for the effective removal of any and all oil components which may be present in the boring or in the apparatus contained therein so as to prevent explosions in the transitional regions between the parts of the apparatus that have been freed from oil and the surrounding oil-containing deposits. In the present invention this is accomplished by subdividing the transitional region into the smallest possible separate spaces and by filling these spaces with sand and gravel so that the propogation of explosion waves will be impeded and promptly stopped in the same manner as in the porous parts of the deposit. The introduction of gaseous mixtures with increasing oxygen contents at ternperatures not over 205 C. will also drive out and oxidize any residual oil from the immediate neighborhood of the boring.

BRIEF DESCRIPTION OF THE DRAWINGS The apparatus for carrying out the improved process is shown in the annexed drawings wherein:

FIGURE 1 shows in cross section a treatment or injection boring inserted into an underground bituminous deposit from the surface of the ground;

FIGURE 2 shows a modified embodiment of FIGURE 1; and

FIGURE 3 is a detailed showing of a modified embodiment of the check valve of FIGURES l and 2.

With particular reference to FIGURE 1, the treatment or injection boring is shown having a casing 1 provided with a perforated liner 20a that extends into the oil -bearing sand 26. The casing is held rmly in place in the surrounding rock 3 by cement 2. A cage 15 is positioned in the casing 1 at the level of the perforated liner 20a adjacent the oil bearing sand. The cage is in the form of a tubular structure with outer and inner jackets of perforated non-corrosive iron. The space between the outer and inner jackets is completely filled with coarse sand while the space inside the inner jacket is partly iilled therewith. A vessel 16 with a fusible bottom 17 is positioned upon the sand in the inner jacket. The vessel is filled to level 19 with a covering liquid such as water containing pieces of the substance such as phosphorus which gnites in the presence of oxygen.

A packer 7 with a peripheral seal 9 is set in the casing 1 above the liner 20a in cage 15. The packer is initially tightly sealed with closure caps 5 and 8 to a horizontal position. A tubing 4 is shown lowered through the pivoted closure caps 5 and 8 and central opening 14 of the packer down to almost the level of the cage 15. The lowermost section of the tube 4 contains an upwardly floating check valve in the form of a ball valve 10, a sealing member 11 and a valve closing spring 12. The tubing 4 carries elastic or resilient centering devices 6 at about 10 meter intervals. Besides their centering function, the devices u also divide the space above the packer into separate compartments 27 to provide better heat insulation for the tube 4.

The free space above the packer 7 between the casing 1 and tubing 4 is filled with nitrogen under pressure or with water, introduced through valve 24.

As shown in FIGURE 2, the packer 7 is shown through which is passed a second tubing 28 with a valve 24 at its upper end. This second tubing 28 permits the introduction of hydrocarbons for combustion and the insertion of a pressure gauge 29 which is lowered by a supporting cable 30 into the cage 15.

A plurality of packers 21 are shown located in the liner 20a for the purpose of controlling the uids introduced into the oil bearing sand 26.

Casing 1 is closed at the top by a cover 23 Which is equipped with a valve 24. Tubings 4 and 28 carry valves 25 and 24 at their upper ends. In the mineral oil industry it is sometimes common practice to provide perforated liners of smaller diameters than casing 1. Such a smaller perforated liner is shown at 20h.

DESCRIPTION OF THE PREFERRED' EMBODIMENTS The process of the present invention is carried out in the apparatus shown in the drawings by first lowering a tubing temporarily into the casing 1 above the packer 7 while the closure caps 5 and 8 maintain the packer secure. Through this tubing an oil solvent or an emulsion thereof in water is introduced in order to remove the residual oil from the casing. Suitable solvents are: gasoline, a mixture of water with alcohols or a mixture of surface active chemical solvents in water or chlorinated hydrocarbons.

The solvent or emulsion is circulated until the casing has been thoroughly cleaned. This temporary tubing is then removed and substituted by the permanent tubing 4 which is lowered into the casing 1 through the central opening 14 of the packer by pivoting the closure caps S and 8 to their vertical positions. The permanent tubing 4 is lowered to almost the level of the cage 15.

Nitrogen under a pressure of about 5 to 10 atmospheres above deposit pressure or water is introduced through the valve 24 into the free space above the packer 7 between the casing 1 and the tubing 4. Heated modified gases of combustion at a temperature of about 200 to 295 C. are now forced through the tubing 4 and through the boring into the oil deposit. After about 48 hours the gases of combustion are gradually enriched with oxygen. This enrichment is continued for another 48 hours until the oxygen content is increased to 21% for the purpose of oxidizing the oil or bituminous residues.

After the deposited oil has been thoroughly removed from the parts of the apparatus and from the immediate neighborhood of the boring so that the porous explosion retarding regions in the deposit can be activated, the temperature of the activated gases of combustion is slowly increased to about 275 to 475 C. These activated gases of combustion consist of carbon dioxide, oxygen and steam. With this increased temperature the readily fusible bottom 17, formed for example from tin having a melting point of 232 C., of vessel 16 melts so as to lose the protective liquid therein and the pieces of phosphorus 18 are ignited by the oxygen.

In an alternative form vessel 16 also contains a catalytic agent such as platinum to initiate in situ combustion with the formation of a burning front between two specially prepared borings.

As particularly shown in FIGURE 2, the second tubing 28 facilitates the introduction of hydrocarbons for combustion until the oil content of the burning space is suficiently high to support combustion.

When the second tubing 28 is no longer needed for the introduction of fuel, a pressure gauge 29 is lowered by the supporting cable 30 into the cage 15. Fluid pressure readings are transmitted by the cable to above ground. The flow resistance encountered by gas and steam, e.g. by the activated gases of combustion, in the regions of combustion is usually very slight. This flow resistance has to be kept practically constant in the regions between the treatment and leading borings. Increased flow resistance can result, for example, from the penetration of flooding water into the path of combustion. In a particular embodiment an increased pressure reading on the pressure gauge activates an increase in the amount of oxygen that is added to the gases of combustion so as to increase the underground permeability to gases.

According to another embodiment, when activated gases of combustion of different compositions are introduced at different levels of the deposit, the cage or basket is perforated only below the level of the uppermost packer 21. The activated gases of combustion having different compositions are introduced separately from above ground through tubing 28 to the upper strata and through tubing 4 to the lower strata.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specic embodiment is, therefore, to be construed as fairly illustrative and not limitative of the remainder of the specification and claims in any way whatsoever.

Example Before the in situ combustion is started, 500 cu. meters per hour of modied gas of combustion at normal conditions is introduced during a period of 48 hours through the apparatus shown in FIGURE 1. This modified gas of combustion comprises S51-20% steam, 41.5il5 CO2 and 3.5111067?) nitrogen. Under a gauge pressure of 85 atmospheres in the deposit, the condensation temperature is about 295 C. so that at the foot of the boring this temperature builds up with the displacement of large amounts of mineral oil. The fusible bottom 17 of vessel 16 now releases the ignition material. During the next 48 hours the modified gas of combustion is changed by continually increasing the oxygen content to 21% from its initial composition of 53 t20% steam, 39il5% CO2,

Sli-10% N2 and 3i10% O2 so that a weakly activated gas of combustion of the composition 40.21-20% steam, 35il5% CO2, 3.8i10% N2 and 21.0i10% O2 is present. With this weakly activated gas of combustion the in situ combustion in the boring and in its immediate neighborhood proceeds at a lower temperature.

Prom the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and condi tions. Consequently, such changes and modifications are properly, equitably and intended to be, within the full range of equivalence of the following claims.

claim:

1. In a process for the production of bitumens from underground deposits containing liquid bitumens by in situ combustion comprising:

(a) locating at least one relatively deep flooding boring, at least one relatively shallow production boring, at least one treatment boring and at least one leading boring, said treatment and leading borings located between said flooding boring and said production boring and spaced a predetermined direction apart from one another in the stratum of an underground deposit of bitumens; and

(b) introducing into said treatment boring an activated gas of combustion comprising oxygen and hot moditied gas of combustion comprising steam and carbon dioxide; the improvement comprising a preliminary preparation of the treatment boring and ignition of an in situ combustion, said treatment boring comprising a casing having an upper end, a lower end and a packer intermediate said ends and said preparation and said ignition comprising:

(c) filling the space defined in said treatment boring between the upper end and said packer -with a material selected from the group consisting of nitrogen under pressure and water whereby traces of oil are removed from the space;

(d) introducing said hot modified gas of combustion comprising steam and carbon dioxide having a temperature above 200 C., depending on the pressure and saturation temperature of said steam, to narrowly restricted spaces in said treatment boring defined by said packer and said lower end and in the immediate neighborhood of said treatment boring;

(e) increasing the oxygen content of the hot modied gas of combustion from 0` to 21% by volume whereby said activated gas of combustion is formed;

(f) increasing the temperature of said activated gas of combustion; and

(g) contacting said activated gas of combustion with substances selected from the group consisting of those which react with oxygen and combustion catalysts whereby burning is initiated at said lower end of the treatment boring.

2. The method of claim 1, wherein the temperature of said hot modified gas of combustion of (d) is about 200 to 295 C.

3. The method of claim 1, wherein said oxygen content of (e) is increased over a time period of about 48 hours.

4. The method of claim 1, wherein said activated gas of combustion of (f) is increased to about 275 to 475 C.

5. The method of claim 1, wherein said nitrogen pressure of (c) is about 5 to 10 atmospheres above deposit pressure.

References Cited UNITED STATES PATENTS 2,804,146 8/1957 Crawford 166-11 2,839,141 6/1958 Walter 166-40 X 3,024,841 3/1962 Willman 166-11 3,127,935 4/1964 Poettmann et al 166--11 3,276,518 10/1966 Schlicht et al. 166-11 3,316,962 5/1967 Lange 166-11 3,344,856 10/1967 Lange 166-11 X 3,360,044 12/1967 Lange 166-40 X STEPHEN I. NOVOSAD, Primary Examiner U.S. Cl. X.R. 

